Electronic code pulse transmitting circuit



Dec. 25, 1951 w. H. T. HOLDEN ELECTRONIC CODE PULSE TRANSMITTING CIRCUIT Filed oomy 17, 195o A 4 Sheets-Sheet l ATronA/EK Dec. 25, 1951 -W- H, T, HQLDEN 2,580,095

ELECTRNIC CODE PULSE TRANSMITTING- CIRCUIT Filed 0017. 17, 1950 I 4 Sheets-Sheetl 2 N n Q g g /N VEA/TOR L k By W. H. 7.' HOLDEN D w N )14M l Arrow/EV WH Hl Dec. 25, 1951 Filed Oct. 1'7, 1950 w. H. T. HOLDEN 2,580,095

ELECTRONIC CODE PULSE TRANSMITTING CIRCUIT 4 Sheets-Sheet 3 MARKER CONNECTOR AfTORNEV Dec. 25, 1951 w. H. T. HOLDEN vELECTRONIC CODE PULSE 'IRANSMITTING CIRCUIT 4 Sheets-Sheet 4 Filed OCT'. 1'7, 1950 wmv ATTO/PNE? Patented Dec. 25, 1951 ELECTRONIC CODE PULSE TRNSMITTING CIRCUIT William H. T. Holden, Pasadena, Calif., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application October 17, 1950, Serial No. 190,492

3 Claims.

This invention relates to telephone systems and has for its object greater efliciency in transferring designations from one oflice to another.

In automatic telephone systems, particularly those employing cross-'bar switches, for example as shown in the application of A. J .Busch,'Serialy No'. 57,394, flied October 2,9, 1948, when a call is to be extended from one cnice to another office, all or a part of the called line designation must be transmitted to the second oice. an outgoing sender at the rst oiiice is connected over the intero'iice trunk which will be used for conversation to an incoming register at the sec- A' ond cnice.

Designations may be transferred by many types of signals including numerical dial type pulses, various codes of direct-current pulses and codes of alternating-current pulses. A preferred form .of alternating-current code employs five frequencies, two of the five frequencies representing each digit, the two frequencies being transmitted simultaneously. The pulses representing the various digits are sent in sequence and it has been customary to employ chains of relays to control this sequential operation.

In accordance with the present invention a series of gas-lilled tubes is employed for controlling the sequential sending of the code pulses, each tube serving to enable the two alternatingcurrent generators selected by the corresponding register to thereby transmit the appropriate code.

The invention will be more clearly understood from a consideration of the following description Yin connection with the drawings in which:

Fig. l is a diagrammatic showing of a system to which the invention is applicable;

Fig. 2 shows the steering circuit and a plurality of registers;

Fig. 3 shows one type of alternating-current f generator;

A,Busch application for a description of the operations oi' a complete system which have been omitted from the present disclosure or only brieny described therein.

Referring first to Fig. l,.when the subscriber vat station initiates a call, his line is connected with a register sender (not shown) inwhich he To d0 this,

registers the'designation of the wanted line. The register sender then calls in a marker and transfers the designation to the marker. The marker translates that part of the designation identifying the oice in which the Wanted line is located and selects a trunk outgoing to that cnice. Having also determined that the cnice is one requiring alternating current code pulses, the marker selects a sender including the apparatus disclosed, transfers the line designation to the digit storing relays i12 of the selected sender and operates the trunk connector |03 to connect the sender with the selected trunk. The marker then connects with and operates the line link switches |64 and trunk link switches |05 to connect the calling line with the trunk and releases.

The seizure of trunk |06 causes the register connector lill to connect an incoming register with trunk |06. When the register is ready to receive pulses, it causes the trunk supervisory circuit |08 at the called oice to transmit a signal over trunk |||6 which is repeated by the trunk supervisory circuit |09 at the calling office to the sender.

In response to this signahthe digit steering chain Ilil functions to successively enable those two of the oscillators which have been selected by the digit storage relays |02, the enabled oscillators transmitting alternating current over pulsing circuit |2 which has been extended to the receiving equipment of the register at the wanted ofce. ItL may be noted that the talking circuit is held disconnected from the trunk during the designation transfer by means of the trunk splitting circuits ||3 and |21.

In the register, the alternating current code signals are received by a limiter amplifier H5. tuned lters H6, rectiilers and detectors H8 which selectively operate the registers H9 which are successively rendered responsive by the steering chain |20. Each designation is preceded by a start signal which operates start circuit |2| to initiate the operation of the steering chain |2|l, the steering chain 2l) being advanced in response to the reception of each digit under the control of the chain advance circuit |23. Following the last digit an end signal is sent whichoperates the end circuit |22.

The end circuit |22' in turn operates marker connector |24 which connects an idle marker |25 with the register, whereupon the registered designation is transferred to the marker |25 which in turn connects with and operates trunk link switches |26 and line link switches |21 to connect trunk |06 with the wanted subscribers line 3 |28. The trunk splitting circuits I3 and H4 now operate to disconnect the sender and register and complete the talking connection between substations and |28. Ringing and supervision takes place in the well-known manner.

Suitable `Vcircuits for the register at the called oice may be :found 'in applicants copending application, Serial No. 190,493, filed October 17, 1950.

The arrangement according to Fig. will be described first. In Fig. 2 are shown five of theseven registers required for registering the seven digits of a telephone designation, namely, .the -two registers 2|0 and 220 on which the first two letters of the oice name are registered and the ,three registers 250, 260 and 210 on which the hundreds, tens and units digits of the "line number are registered. The two registers, not shown, which would be used to register the third digit of the ofhce designation and the thousands digit of the line designation are substantially the sameas the registers shown.

'Each digit register includes'iive relays, of which the first Ythree .and the last are shown. These relays are operated from the marker through marker connector 300 to register a digit in accordance with a two-out-of-ve code. This code may be illustrated .by the following table,.as applied to register 2|0, assuming thatv the relay which is omitted is numbered 2|MAI1) Digit: Relays registered -0 2|MA4'), 2|5(A1) 1 2| (All) V2 I 2 (Al) .2 `2| I (A0), Y2|3(A2) 3 2|2(A|), 2|.3(A2) 4 2| l (A0), 2 IMAQ) 5 2|2 A|), ZIMAA) 6 2|3(A2), ZIMAA) '7 `2||(A0), 2|5(A1) 8 2|2 A-|), 2I5(A1) 9 2|3(A2), 2|5(A1) The oscillators 3`|0 to 3|8 of Fig. 3 are of the inductance capacity type employingV a pentode tube such as tube 320. These oscillators are individual to the senderand are tuned by the selection of condensers 32|, 322, 323, etc. of such values that the desired frequencies will be generated. The amplitude of the frequency generated is controlled by neon glow lamps 324, 325, 325, etc. The output of the oscillators is connected to a common output transformer 3.21 only when the associated one of the gate glow lamps 328, 329, 339, etc. is energized in themanner to be described.

Six oscillators areprovided, one for each of the ve frequencies required by the digit code and one for use in transmitting start and end signals. These frequencies may lconveniently be as fol- When the Amarker selects the sender, it closes a circuit for oif-normal relay 392, which operates and locks over conductor 303 to ground over the 'back contact of relay 200. Relay 302 Aconnects -1-130-Volt battery to conductor 30| to start the oscillators and to prepare the gas-filled tubes of the steering chain for operation. It also connects ductor 39| through resistance 202 to condenser 293 which is connected to ground through resistance 204 and to the control anode of tube 205 through resista-nce1205. Condenser 203 starts to charge and when the charge reaches the breakdown potential for tube 205, that tube breaks down and relay 201 operates across the main gap.

With relay 201 operated -l-.lSO-volt lbattery from conductor 30| is connected'through resistance 208, left contact of relay 201., conductor .348 through resistance 305 to glow tube 330 which kbreaks rdown .and permits the HOO-cycle output of oscillator 318 `to pass to the output transformer 321. A similar circuit Vis closed from conductor 30| through resistance 209 over the right contact of relay 2.01 and conductor V3112 to the third oscillator (not shown) ywhich generates the '1100- cycle frequency causing that Yfrequency lalso to pass to the output transformer 321. Therefore. a start signal made up of frequencies of `1100 cycles and 1700 cycles is transmitted to the. distant cnice toV prepare the register a't that ofce `to rreceive the digit pulses.

With tube 205 conducting, the cathode potential becomes positive and this ,positive potential is applied through resistance V290 to condenser 29| which charges. Condenser 29| is connected through resistance 292 to the control anode of tube' 293 and when a sufficient charge is built up on condenser 29|, tube 293 breaks down. This breakdown creates a surge through condenser 294 so that tube 295 is extinguished by cathode commutation.

In a similar manner condenser 295 is charged to cause tube 296 to break down, creating a surge through condenser 2.91 to extinguish tube 293. Condenser 298. charges more slowly through the winding of relay 299 which operates in this Vcharging current and is therefore operated fora measured interval .determined by the time required to charge condenser 298.

With relay 299 operated, circuits are closed for enabling two of the oscillators as determined vby the registration setup on register 2|0. Assuming that the digit 1 has been registered, relays 2|| and 2|5 will .have been operated. A circuit is therefore closed from +-volt battery on conductor 30|, resistance 289, right contact of relay 299,`lower front contact of relay 2| I, conductor 340 to glow tube 328 whichV becomes .conducting, permitting the '10D-cycle output of oscillator 3.|.0 to pass to output transformer. 321. A similar circuit is closed from conductor 30| through ,resistance-288 r.left contact ofv relay 299, upper front contact ofrelay 215 .over conductor 341 to the glow tube associatedY with the fifth oscillator, permitting-the G-,cycle output of that oscillator to pass to transformer `321. Therefore, a two-frequency pulse `consisting of `100-cycleand 150G-cycle curent is transmitted to the distant office where it brings about the vregistration of the digit '1.

Similarly, each of the steering tubes is operated, extinguishing the previously operated tube to cause the transmission of two-frequency pulses as determined by they registration on the associated register.

If a complete seven-digit number has been registered and sent out, following the sending of the seventh digit, tube 281 is operated in turn operating relay 2MB. With relay 292 operated a circuit is closed from -l-l30-volt battery on conductor 33|, resistance 236, left Contact of relay 200, conductor 348 to glow tube 330 to operate that tube and cause the T100-cycle output of oscillator 3| 8 to pass to transformer 321. A second circuit is closed from conductor 30| through resistance 235 over the right contact of relay 203 to conductor 341 to render conducting the glow tube associated with the fth oscillator and to cause the 1500-cycle output of that oscillator to pass to the transformer 321. These two frequencies constitute an end signal and tell the distant ofdce that no further pulses are to be expected.

Relay 200 disconnects ground from conductor 303, opening the locking circuit of relay 302. Relay 302 is slow to release and after an interval opens its contacts to remove +130-volt battery from conductor 30|, extinguishing tube 28?, and ground from conductor 304, releasing the register relays and restoring the sender to normal.

If less than seven digits are reglstered, the steering chain functions in the same manner, but with none of the relays of a register operated, no oscillator enabling circuit is closed and no pulse is sent out at that time.

The arrangement according to Fig. 6 differs from that of Fig. 5 chiefly in the form oi oscillator employed. These oscillators 4I0, 4| I, etc. are of the tuned reed type which are energized by a magnet rather thanmechanically. For example, when relay 43| is energized, reed 432 is started and vibrates, transferring energy through a loose coupling to reed 433, which builds up its amplitude gradually as energy passes through the coupling means. Before energy transfer is complete, reed 432 is held magnetically and the vibrations of reed 433 decline in amplitude, energy being drained oi by the coupling. Reed 433 is of magnetic material and as it vibrates it generates an alternating current in output winding 434.

The mechanical oscillators 4H! to 4|1 are tuned to the same frequencies as are the electronic oscillators 3|0 to 3|8. The output windings of oscillators 4|0 to 4|1 are connected in parallel across the conductors outgoing to the trunk. When one of the distributor relays of Fig. 2, for example relay 299, operates it connects +130-volt battery to two of the conductors 340 to 341. Assuming that, as in the case previously described,

M30-volt battery is connected to conductors 340 and 341, the neon glow tubes 420 and 421 become conducting, passing current to the energizing magnets of oscillators 4|0 and 4|1 so that these oscillators generate a pulse of alternating current of frequencies of '100 cycles and 1500 cycles which is transmitted directly to the conductors outgoing to the trunk. The duration of the pulse is determined by the mechanical characteristics of the oscillators, although the steering chain determines the interval between the start of successive pulses.

What is claimed is:

1. In a telephone system a plurality of digit registers, a plurality of alternating-current generators, means under the control of each of said registers for selecting said generators two at a time in accordance with a'predetermined code, an out-pulsing circuit, means to connect said generators with said out-pulsing circuit, a chain of cold cathode tubes corresponding to said registers, means to successively energize said tubes one at a time, and means under the control of each tube to enable the generators selected by the corresponding register.

2. In a telephone system a plurality of digit registers, a plurality of alternating-current generators, means under the control of each of said registers for selecting said generators two at a time in accordance with a predetermined code, an out-pulsing circuit, means to connect said generators with said out-pulsing circuit, a chain of cold cathode tubes corresponding to said registers, means to successively energize said tubes one at a time, and means under the control of each tube to enable the generators selected by the corresponding register comprising a relay and a condenser in the output of each tube, the relay being operated during the charging time of said condenser.

3. In a telephone system a plurality of digit registers, a plurality of alternating-current generators, a neon glow tube individual to each of said generators, means under the control of each of said registers for selecting said generators two at a time in accordance with a predetermined code, an out-pulsing circuit, normally ineffective means including said glow tubes to connect said generators with said out-pulsing circuit, a chain of cold cathode tubes corresponding to said registers, means to successively energize said cold cathode tubes one at a time, and means under the control of each cold cathode tube to operate the glow tubes individual to the generators selected by the corresponding register to render said connecting means effective.

WILLIAM H. T. HOLDEN.

No references cited. 

